what is the best way to jack up sagging roof and where to get the best jacks. heplp I am new to this. pjhalla@gmail.com

Hello, Phillip.

It all depends... My first concern would be why the roof is sagging to begin with? Are the walls spreading, joints failing, the foundation settling, the rafters rotted or undersized, etc.? A sagging roofline can begin in the basement...

Look for clues. A bit of careful measurement,inspection and analysis before jacking anything would suggest what the specific source of the trouble is, and then the best answers to correct it.

Once the underlying reason is understood, the process can be sequentially reversed, then fixed permanently. Might be easier than you expect, if you are lucky...

Pete

I will sometimes use poles to jack barn rafters.
get up there and nail a 2x to the bottom of the rafters. Clear the floor and nail a 2x parallel to the rafter run, a foot or three in from the upper jacking spot. Measure from top to bottom on a tilt, cut your pole so that you can drive the bottom of the pole along the floor of the barn(the lower 2x). Nail the top of your pole to the upper 2x first, or it will fall on you.
This is a bit hard to explain, but will lift the roof easily right off the top plate, using multiple poles spaced 4-8ft apart, depending on the weight of the roof system.